Today is Tuesday, May 26 th, 2015 Pre-Class: Name something the Sun does. That can be a thing it does in space or a thing it does for Earth. Oh, and get.

Today is Tuesday,May 26th, 2015

Pre-Class:Name something the Sun does.

That can be a thing it does in space or a thing it does for Earth.

Oh, and get a small paper towel for you/your partner.

http://www.wired.com/wp-content/uploads/images_blogs/wiredscience/2010/10/twister768.gif The Sun

In This Lesson:Unit 4

The Sun(Lesson 1 of 2)

Today’s Agenda

• “Here comes the Sun…” (do-do-doo-do)– It’s all right…

• Solar structures• Solar behaviors• A multimillion dollar pseudo-failure.

• Where is this in my book?– Chapter 11 (pages 323 – 348).

By the end of this lesson…

• You should be able to describe the path a photon of light takes from the core of the Sun outward to Earth or another destination.

• You should be able to identify and explain patterns of solar behavior.

Our last unit…

• …featured comets, among planets and other space debris.

• In reality, though, in astronomy, planets (and humans) are not the stars of the show.– See what I did there?

Da Sun

• Furthermore, even gravitationally, something else is at the center of this story.– The Sun.

• I hope you got the sense that a comet hitting Earth would be a very, very bad thing.

• But what about a comet hitting the Sun?– NASA Captures Giant Comet Hitting Sun

Perspective

• The usual size perspective:– The Largest Star

• And for what will become our closure bookend video, watch this next video closely.– It’s years and years of data from NASA’s SDO (Solar

Dynamics Observatory).– Take in the images – we’ll add our own narration

at the end of the lesson.– NASA Solar Dynamics Observatory

Your Introduction

• We’re going to do a little reading from good ol’ Discover magazine to introduce the Sun.– I think you’ll find the Sun is a bit more involved in

your life than you might have guessed.• Forecasting the Sun’s Weather reading

The Sun and You:Distance Makes the Heart Grow Cooler

• The Sun has a hand in a lot:– Light– Warmth– Wind– Food– Keeping us in the right part of the solar system…

• So it’s kinda important to us.

The Sun and You:Distance Makes the Heart Grow Cooler

• Okay, it doesn’t literally have hands.– Or gloves.– Or a tongue.– Or teeth.

• Whoa. Chill out there, Sun.• Okay, okay, I’m sorry.• Hey, this doesn’t concern you, Moon.• Beat it.

http://www.clipartbest.com/cliparts/yio/A4n/yioA4nyiE.jpeg https://whisperinggums.files.wordpress.com/2011/02/sunclkerocal.png?w=600http://thumbs.dreamstime.com/t/sun-moon-personified-grinning-frowning-30362467.jpg

So what does the Sun have?

• Magnetism.– The Sun is the single most magnetic object in the solar

system.• So it has poles, like Earth, and they switch every so often, like

Earth (though in the Sun’s case it’s every 11 years).

– The magnetism is generated by granulation regions (more later) and by larger features like sunspots (more later).

• Magnetism is going to explain virtually everything else we learn about the Sun.– Keep that in mind. It’s the “why” for most of the lesson.

So what else does the Sun have?

• Suppose you were sent by a criminal mastermind (some crazy 1970s James Bond villain or something) to a prison located in the center of the Sun.– Better bring sunscreen.

• SPF 9,000,000,000 should do it.

• Through which layers of the Sun would you pass on your escape?

For your notebooks…

• Draw a shape like this one, leaving room to add labels and definitions.– It’s 6 layers, plus one

more for the wavy stuff outside it.

Not to scale.

Solar Layers: Core

• Your starting point is the Sun’s core.– Like the outer planets, it’s not really a

rocky surface.– Instead, it’s gas that has been

compressed to densities not paralleled in any of the familiar parts of Earth.

• Because the Sun is so big, pressure grows immensely.– Temperatures here reach 15,000,000 K

(27,000,000 °F).– Atomic structure is destroyed –

making plasma – and kick-starting fusion reactions.

Plasma and Fusion Reactions

• Let’s remind ourselves of the structure of the (typical) atom:– Protons (+) and neutrons (0) in the nucleus.– Electrons (-) around the nucleus.– A single proton can also be written as H+.

• Because of the intense heat and pressure inside the core, atoms get broken apart.– Neutrons leave the core.– Protons (hydrogen nuclei) get slammed together into

helium (He), generating a great deal of energy.


• Technically there’s a lot of quantum physics wizardry going on in that fusion reaction I just described, with sub-subatomic particles and antimatter like neutrinos and positrons abounding.– Plus, technically some of the He mass is lost as energy.

• Worry not about those, instead, just keep in mind:– The Sun combines hydrogen atoms into helium atoms

through fusion reactions powered by intense pressure and heat.

– The fusion process is known as the proton-proton (P-P) chain.


http://solar.physics.montana.edu/ypop/Spotlight/SunInfo/fusion.html

FAQ: Gamma Rays

• Q: Aren’t gamma rays dangerous? It looks like the Sun is making a lot of them. Since they don’t get deflected by the magnetic field of Earth, what’s stopping them?

• A: They are dangerous and the Sun does make a lot of them. However, they’re made in the core of the Sun and have a long way to go to get out of the Sun and toward Earth. In that exit process, they get attenuated down to visible light photons. It takes that gamma wave photon around 170,000 years to exit the core anyway.

Sun Structure

Core(hot, fusion reactions)

Not to scale.

Solar Layers: Radiation Zone

• Surrounding the core is the radiative zone (also known as the radiation zone).– Here, atoms pass the energy gained

from the fusion reactions in the core from one atom to another (aka, radiation).

• Because the radiation process is random (energy may move outward or inward), it takes around 170,000 years for it to emerge from the radiation zone.http://solar.physics.montana.edu/ypop/Spotlight/SunInfo/randwalk.html

Sun Structure


Radiative Zone(heat passed between atoms)

Not to scale.

Solar Layers: Convection Zone

• Surrounding the radiation zone is the convection zone.– Convection, like a convection

oven, involves the movement of atoms of high energy, not simply a passage of energy between atoms.

• The density here is lower, so atoms (in large groups) move up when they have a lot of energy, rising toward the Sun’s surface.

http://solar.physics.montana.edu/ypop/Spotlight/SunInfo/convect.html

Sun Structure



Not to scale.

Convection Zone(matter rising/falling)

Convection?

• If the idea is confusing, consider this:– Hot air _____.

• Rises, right?

• But why does hot air rise?– It’s not because of the temperature.– It’s because it’s less dense.

• In the same way, warm ocean water currents tend to be near the surface and hot gas bubbles rise out of a pot of boiling water.– For the Sun, that means blobs of material rising to the

surface and then sinking back down once they’ve released energy.

Back to the analogy…

• Suppose, during your escape from your solar prison, observers from Earth try to watch your progress.

• Unfortunately, so far they cannot see you.– The gas density is so high, even at this point, that it blocks

conventional views.• Thankfully, the inner parts of the Sun can still be studied

using helioseismology.– It’s a relatively new field that looks at vibrations and

oscillations of the Sun’s inner parts to determine its composition.

– Similarly, geoseismologists study the Earth’s composition through earthquake vibration transmission.

Solar Zones

http://solarscience.msfc.nasa.gov/images/cutaway.jpg

Solar Layers: Photosphere

• Finally, on your journey outward, you reach the very thin photosphere.– Quite literally, “ball of light.”

• This is the visible surface of the Sun.• Because of the convection zone

beneath it, we see regions where material is rising and regions where it is falling.– The resulting pattern is called

granulation.http://solar.physics.montana.edu/ypop/Spotlight/SunInfo/Photosph.html

Granulation

• Each granule is a convective cell, with material rising in the bright center but falling along the darker, bordering lanes:

http://astrobites.com/wp-content/uploads/2012/07/kauf18_4.jpghttp://cdn.phys.org/newman/gfx/news/hires/3-newinsightsi.jpg

Other Features of the Photosphere

• Supergranules are, well, big granules.

• Sunspots are like dark blemishes on the surface.– They feature lower

temperatures but higher magnetic field strength.

– They usually come in twos.– The dark region is the umbra,

surrounded by the penumbra.http://solarscience.msfc.nasa.gov/images/sunspot1.jpg


• Like sunspots, faculae are areas of stronger-than-normal magnetic field.

• Unlike sunspots, faculae are brighter than the rest of the surface of the Sun.– Even though they look

darker in the black-and-white picture over there.

http://solarscience.msfc.nasa.gov/images/faculae.jpg


• Solar flares are perhaps the most dramatic events that occur in the photosphere.– Think of them like a volcanic eruption on the Sun,

except instead of lava exploding out, it’s electromagnetic radiation.• Radiation in the form of visible light, infrared light, gamma

rays, radio waves…you name it.

– Also, the energy released is on the order of 10,000,000x that of a volcanic eruption, but still small compared to the Sun’s total energy output.

http://hesperia.gsfc.nasa.gov/sftheory/flare.htm

Solar Flares

• In three steps, a solar flare:– Builds up – the precursor stage.– Is released – the impulsive stage.– Winds down – the decay stage.

• To an observer on Earth, these appear as bright flashes of light.– It’s caused by reorientations in the magnetic field.

• Let’s watch…– Fiery Looping Rain on the Sun– Solar Flare – Magnificent Eruption

Sun Structure



Not to scale.


Photosphere(visible surface, granulation)

Solar Layers: Chromosphere

• Now above the photosphere and visible to observers on Earth, you next move to the chromosphere, the “sphere of color.”– It gets its name from the red

wavelength light emitted by H.– Here, convection continues to

transmit energy.

http://sunflowercosmos.org/cosmology/the_sun_images/12_sun_spicules.jpg

Other Features of the Chromosphere

• Filaments are dark “threads” made of cool material, suspended over the surface by magnetism.

• Plage are bright areas around sunspots.

http://solarscience.msfc.nasa.gov/feature2.shtml#Prominences

Filaments and Plage

http://solarscience.msfc.nasa.gov/images/H_I_6563.gif

Other Features of the Chromosphere• When filaments extend out

past the solar limb (edge), they’re called prominences.– FYI, prominences are different

from solar flares in that prominences are generally tame.• Violent prominences are effectively

solar flares, and violent solar flares may be termed coronal mass ejections (CMEs).

• Spicules are like little “flames” shooting off the chromosphere.

http://solarscience.msfc.nasa.gov/images/prominence.jpghttp://solarscience.msfc.nasa.gov/images/spicules_color.jpg

Prominences

Spicules

Sun Structure


Radiation Zone(heat passed between atoms)

Not to scale.



Chromosphere(filaments, plage, spicules)

Solar Layers: Transition Zone

• It’s been rather hot all through this journey of yours, but thus far things have actually been cooling as you go from the inside out.

• Oddly, as you exit the chromosphere, you notice an uptick in temperature.– “Uptick” as in 20,000 K in the

chromosphere to 2,000,000 K in the corona.

• The region of sharp temperature change is the transition zone.

Transition Zone

http://solar.physics.montana.edu/ypop/Spotlight/SunInfo/transreg.html

Sun Structure



Not to scale.



Chromosphere(filaments, plage, spicules)

Transition Zone(increase in temperature)

Solar Layers

• On the last part of your escape, you’d enter the corona.– The Sun’s outer atmosphere and

hottest point – over 1,000,000 °C.– It’s what becomes visible during a

solar eclipse.– Solar flares reach from the

photosphere all the way out to the corona when they erupt.

– Separately, the corona is responsible for the solar wind.

http://solar.physics.montana.edu/ypop/Spotlight/SunInfo/helmet.html

The Corona

http://i.telegraph.co.uk/multimedia/archive/01594/corona-large_1594047a.jpg

• Helmet streamers are peaks in the corona above sunspots, prominences, or filaments.

• Polar plumes are “streamers” from the corona at the poles of the Sun.

• Coronal mass ejection (CME) is the general term for a violent outgassing of the corona.

http://solarscience.msfc.nasa.gov/images/helmet_streamer.jpghttp://solarscience.msfc.nasa.gov/images/eit020.jpg

Helmet Streamers

Polar Plumes

Other Features of the Corona

Other Features of the Corona

• Coronal loops are, well, loops of corona.– They may be associated with

flares; they may not.– Coronal Loops video

• Coronal holes…figure it out.– They’re often found at the poles.– Even though they’re dark, they

seem to be the source of the fastest parts of the solar wind.

Coronal Loop

Coronal Holehttp://solarscience.msfc.nasa.gov/images/Yohkoh_920508.jpg

Sun Structure



Not to scale.



Chromosphere(visible surface, granulation)

Transition Zone(increase in temperature)

Corona(visible during eclipses)

Solar Structures Visual Review

• To the computers!

What is the Solar Wind?

• The solar wind, as we’ve seen, is a constant stream of radiation from the Sun.

• In fact, it’s perhaps best thought of as a very thin gas sent through space.

• To learn more about it, NASA launched the Genesis spacecraft in 2001, designed to collect (yes, collect) some of the solar wind and return it to Earth.

Genesis

• In September 2004, Genesis was due back to Earth.• On its way through the atmosphere, the craft’s

deceleration sensor never worked (it was installed backwards).

• The parachute never deployed, sending the return capsule crashing into the desert in Utah.

• Thankfully, NASA scientists were able to recover some of the samples collected and still learned something about the nature of the solar wind.– Mainly about the composition of the solar wind and its effects

on materials, since they still managed to get a pure sample.

Sun Structure Summary Slide#theletterS

• Core• Radiation Zone• Convective Zone• Photosphere– Sunspots, faculae, granules, supergranules.

• Chromosphere– Solar flares, spicules, prominences, plage, filaments.

• Transition Zone• Corona– Helmet streamers, polar plumes, coronal loops/holes.

Sunspot Cycles

• What Patterns are Revealed by Sunspots? activity

• Solar Weather Interactive

Other Features of the Sun: Cycles

• The sunspot cycle is 11 years on average.– Sunspots seem to occur in waves, with many

happening at once and then, at other times, only a few.

• The solar cycle is 22 years on average, and features the flipping of the North and South magnetic poles twice (returning to the original N-S orientation after the full cycle has completed once).

Other Features of the Sun: Rotation

• The Sun rotates once every 27 days.– It’s averaged to 27

since the Sun is all gas and different parts rotate at different rates.• The equator rotates

once every 24 days, but the poles take around 30 days.

The Future of the Sun

• Let’s return to the core of the Sun for a moment.– “No! I can’t go back there, no!”

• We talked about how the Sun fuses hydrogen atoms into helium atoms.

• How much hydrogen does it have?– The Sun is about 75% H and 25% He, with metals existing in

trace quantities.• That hydrogen fuel is due to run out in 7 billion years,

but in the meantime, it’ll be getting warmer.• And that’s the topic for our next lesson: stars and their

life cycles.

Solar Observations

• Let’s go outside and (safely) stare at the Sun.• An important note:– We’re using a telescope with a specially-designed

solar filter that blocks the vast majority of the Sun’s light and radiation.

– Using the scope to observe the Sun directly without the filter would cause immediate and irreversible damage to your eyes.

• In other words, don’t do this without adequate preparation.

Closure

• NASA Solar Dynamics Observatory video (again)

• UniverseToday – How Many Ways Can the Sun Kill You

Today is Tuesday, May 26 th, 2015 Pre-Class: Name something the Sun does. That can be a thing it does in space or a thing it does for Earth. Oh, and get.

Documents

grinningfrownin slide

solar system

patterns of solar behavior

cooler okay

years of data

heart grow cooler

giant comet

bad thing